Tap for cutting spiral wedge nuts



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atented Mar. 27,1883.

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UNITED STATES PATENT OFFICE.

HAYNVARD A. HARVEY, 0F ORANGE, NEW JERSEY.

TAP FOR CUTTING SPIRAL WEDGE-NUTS.

SPECIFICATION forming part of Letters Patent No. 274,492, dated March 2'?, 1883. i

Application filed Noveinliet l4. i882. (No modeLl To tl-l who-m it maij concern Be it known that I, HAYWARD A. HARVEY, ot' Orange, New Jersey, have invented a. certain Improvement in Taps for Cutting Spiral Wedge-Nuts, of which the following is a speciiication.

The tap which I have invented for this purpose is provided Vwith a th readot' uniform pitch, the convolutious ot' which, iu the forward portion of the tap, have comparatively narrow bases and steeply-inclined sides, while the consecutively adjoining convolutions have their bases progressively widened and their sides graduallydiminished in steepness. At its forward end it is tapered, and is provided with a suitable number of convolutions ot a groove which has a ilat bottom, forming obtuse angies with the sides ot' the threads. The intermediate section ot' the tap is provided with a tiet-bottomed spiral groove, the bottom of which gradually diminishes in width, its angles with the sides ot' the thread gradually diminishing in obtuseness until the sides of the thread meet. l

In the accompanying drawings, illustrating a tap embodying my invention, Figure l is an elevation, and Fig. 2 is a central longitudinal suction.

The drawings represent a tap, A, provided with a screw -thread of unitorm pitch, rendered discontinuous h v the usual longitudinal grooves, A'.' The forward section, c, ot' the tap has the usual taper, and is provided, as

Y will he seen, with a dat-bottomed spiral groove.

In the middle section, b, of the tap the angles of thesidesot' the thread with the dat-bottomed groove gradually change. The bottom of the groove gradually diminishes in width until the sides of the thread meet, forming the triangular grooves of the several convolutions of the heel-section a of the tap.

`It will he seen that by a. single insertion of this tap into a. nut-blank there will be cut in the blank, first, a number of convolutions of a truncated thread, then a number of convolu tions of a truncated thread graduallymerging into a V-thread by the progressive narrowing ot' its apex, and, iinally, a number of convolutions of a Vtbread.

In Letters Patent of the United States No. 224,591, dated February 17, 1880, granted to me for improvement in lock-nuts, l described a method of making a nut of this character hy the use ot' two taps, the one cutting a truncated thread throughout the entirel length of the holethrongh thenut-blank, and theotheradapted to gradually transform the truncated th read into a V-thread.

By my present invention, as will be seen, yl am enabled with a single tap to perform the entire operation of cutting the thread in a nut ot' the character described.

' I claim as my invention- A tap 'orcutting spiral wedgennts, substantially such as herein described, the same consisting ot'a tap having the usual taper at its forward end, and the usual longitudinal grooves, and provided throughout with a spiral thread otA uniform pitch, the convolutions otl which, in the forward portion of the tap, have sides forming excessively acute angles'with each other, by which this portion of the tap is adapted to outl a certain number ot con volutious of' a truncated thread in the nut, while the adjoining convolutions of the thread in the middle section 'of the tap have sides the angles ot' whichy relatively to each other gradually diminish in acuteness, by which the middle section of the tapis adapted to cut a certain number of con'- volutions of the nut-'thread in the form of truncated threads with progressively narrowing apioes, and the remaining or heel section ot' the tap has a thread the convolutions ot which are alike in their area and shape in cross-section, and are thusadapted to cut a number ot' similarly lilreconvolutionsofthread in the nur.

' H. A. HARVEY. Witnesses ASA FARE, M. L. ADAMS. 

